2D PN Junction Diode Simulator

This 2D cross-section simulator shows a silicon PN junction diode from the side: p-type material packed with mobile holes on the left, n-type material packed with mobile electrons on the right, and the depletion region between them where fixed dopant ions create a built-in electric field. Drag the bias slider from reverse through zero into forward bias to watch the depletion region shrink as the barrier collapses, current stay essentially zero until the ~0.7V silicon threshold is crossed, and the band diagram below flatten as the junction turns on — then push it further negative to see the depletion region widen and block conduction under reverse bias, with only a trace of leakage current getting through. The doping slider shows how a heavier dopant concentration compresses the depletion width and sharpens the turn-on.